Compressor lubrication system

ABSTRACT

A refrigerant compressor has a vertically extending crankshaft with its lower end in an oil sump. An off-center bore extends vertically within the crankshaft, and is connected through radial bores to the bearings. The bottom of the off-center bore is connected to the outlet of an oil pump formed in the bottom of the crankshaft. The inlet of the oil pump is connected to the oil in the sump. A gas pump is formed in the lower portion of the crankshaft above the oil pump. The gas pump has its inlet connected to the inlet of the oil pump, and has its outlet connected through a radial bore in the crankshaft to the space above the sump. Another gas pump is formed in the upper portion of the crankshaft and has its inlet connected to the top of the off-center bore, and its outlet within the interior of a motor compartment above the off-center bore.

[ 1 3,736,076 [451 May 29,1973

[54] COMPRESSOR LUBRICATION SYSTEM [75] Inventor: Robert W. Ayling, Briston, Va.

[73] Assignee: Cardinal Compressor Corporation,

Bristol, Va.

[22] Filed: Mar. 1, 1972 [211 Appl. No.: 230,652

[52] US. Cl. ..4l7/372 [51] Int. Cl ..F04b 39/02 [58] Field of Search ..4l7/902, 368, 372, 417/424 [56] References Cited UNITED STATES PATENTS 3,049,285 8/1962 Doeg ..417/372 3,098,604 7/1963 Dubberley ..417/372 3,182,901 5/1965 Solomon ..4l7/372 3,285,504 11/1966 Smith ..4l7/372 9/1972 lida et a1 ..417/372 Primary Examiner-Carlton R. Croyle Assistant Examiner-Richard J. Sher Attorney-Robert T. Palmer [57] ABSTRACT A refrigerant compressor has a vertically extending crankshaft with its lower end in an oil sump. An offcenter bore extends vertically within the crankshaft, and is connected through radial bores to the bearings. The bottom of the off-center bore is connected to the outlet of an oil pump formed in the bottom of the crankshaft. The inlet of the oil pump is connected to the oil in the sump. A gas pump is formed in the lower portion of the crankshaft above the oil pump. The gas pump has its inlet connected to the inlet of the oil pump, and has its outlet connected through a radial bore in the crankshaft to the space above the sump. Another gas pump is formed in the upper portion of the crankshaft and has its inlet connected to the top of the off-center bore, and its outlet within the interior of a motor compartment above the off-center bore.

14 Claims, 2 DrawingFigures COMPRESSOR LUBRICATION SYSTEM BACKGROUND OF THE INVENTION -Many piston type refrigerant compressors have vertically extending crankshafts with off-center bores connecting through radial bores with bearings, and having their bottoms within oil sumps. Centrifugal pumps formed in the bottom portions of the crankshafts have their outlets connected to the bottoms of the off-center bores, and their inlets connected to the oil within the oil sumps. The lubricating oil for such compressors is in contact with the refrigerant so that the oil draining into their oil sumps contains absorbed refrigerant, and hence is volatile. Gas within the oil flowinging' through such oil pumps may interfere with the flow of oil, and result in the starving of the bearings. This problem is well known, and there have been many efforts to solve it. My U. S. Pat. No. 3,259,307 discloses the formation of a centrifugal gas pump within the upper portion of a crankshaft for removing gas from the oil within an off-center oil supply bore. My and Paul G. Thavers joint U. S. Pat. No. 3,388,855 disloses the formation of a centrifugal gas pump within the lower portion of a crankshaft for removing gas from the oil entering an oil pump. The present invention is an improvement of the inventions of both of such patents as will be described later in connection with the explanation of the operation of this invention.

SUMMARY OF THE INVENTION A piston-type refrigerant compressor has a vertically extending crankshaft with the rotor of an electric driving motor keyed to its upper portion. The bottom of the crankshaft is within an oil sump. An off-center bore is connected through radial bores with the bearings, and is connected at its bottom to the outlet of a radial oil pumping bore within the crankshaft near the bottom of the latter. The inlet of the oil pumping bore is connected through a central bore in the bottom portion of the crankshaft to the oil within the sump.

For removing gas from the oil at the inlet of the oil pumping bore, the top of the central bore is connected through another central bore smaller in diameter than the first mentioned central bore, and an orifice between the latter and a radial bore extending through the crankshaft from its axis and through a counterweight formed on the crankshaft to the space above the oil sump. The other central bore, the orifice, and the radial bore through the crankshaft and the counterweight form a centrifugal gas pump for removing gas from the inlet end of the oil pumping bore. Centrifugal force and the orifice oppose the flow of oil through the gas pump.

For removing gas from the oil within the upper portion of the off-center bore, the top of the latter is connected through a transverse bore crossing the axis of the crankshaft to a keyway formed in adjacent surfaces of the crankshaft and the rotor of the motor. A hollow key extends within the keyway above the transverse bore. The keyway below the key connects with the bottom of the opening within the key. The top of the opening within thekey is at the top of the crankshaft, and discharges gas into the upper portion of the motor compartment. The transverse bore forms a centrifugal gas pump for removing gas from the upper portion of the off-center bore, the gas so removed flowing through the keyway below the key, and through the opening within the key into the upper portion of the motor compartment. Centrifugal force opposes the flow of oil through the transverse bore.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 of the drawings is a side elevation, partially in section, of a refrigerant compressor embodying this invention, and

FIG. 2 is an enlarged section through the crankshaft and the keyway of the compressor, the section being taken along the lines 22 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION An upper shell around the upper portion of a motor compartment 11 is attached to an intermediate shell 12 which is attached to a lower shell 13 extending around the lower portion of the assembly. The lower shell 13 forms an oil sump 15. An electric motor 16 has a rotor 17 attached to a vertically extending crankshaft by a hollow cylindrical key 18 within a cylindrical keyway 19 formed within adjacent surface portions of the rotor 17 and the crankshaft 20. The latter has a crankpin 21 on which eccentric straps 22 and 23 are journalled. The strap 23 is connected to piston 24 operating within cylinder 25. Valve plate 26 at the top of the cylinder is held in place by a cylinder head 27. The strap 22 is connected to a piston (not shown) operating within a cylinder having a head 28. The cylinder heads 27 and 28 are connected by discharge gas tubes and 36 respectively, to a conventional muffler 37 which is connected by conventional tubing (not shown) to the outlet of the motor-compressor unit. A suction gas tube 40 connects through the shell 10 with the motor compartment 11 as is conventional.

Formed to the cylinders is an upper bearing housing 41 around upper bearings 42 and 43 which are around the crankshaft 20 near the bottom of the motor 16. Attached to the cylinders is a lower bearing housing 45 for a lower bearing 46 around the lower portion of the crankshaft 20. The housing 45 extends into the oil sump 15 under the bottom of the crankshaft 20. There is a thrust bearing 47 between the bottom of the crankshaft 20 and the upper surface of the housing 45 opposite thereto. The housing 45 has an opening 48 below the axial center of the crankshaft 20, connecting the oil sump 15 with a lower central bore 49 within the crankshaft 20. The bore 49 is connected by a radial bore 50 within the crankshaft 20 to a vertically extending, offcenter bore 51 within the crankshaft 20, and by radial bore 53 within the crankshaft 20 to the lower bearing 46. The radial bore 50 connects with annular space 52 in the lower bearing housing 45. The off-center bore 51 is connected by radial bore 55 within the crankshaft 20 to the upper bearing 42.

A counterweight 56 is formed on the lower portion of the crankshaft 20. A plate 57 is clamped at the junction of the shells l2 and 13, and supports the motorcompressor assembly. The plate 57 has openings 59 for the drainage of oil and refrigerant from the motor compartment 11 into the sump l5.

The bores 49 and 50 form a centrifugal oil pump for forcing oil from the sump 15 through the off-center bore 51 and the radial bore 53 to the bearing 46, and through the off-center bore 51 and the radial bore 55 to the upper bearing 42.

The construction described so far with reference to the drawings, except for the plate 57 which forms no part of the present invention, is not novel. The present invention adds, for venting accumulated gas separated from the oil in the central bore 49, a radial bore 60 within the crankshaft 20 and the counterweight 56, the outer end of which connects with the space within the compressor just above the plate 57. The inner end of the radial bore 60 extends inwardly just beyond the axis of the crankshaft 20, and connects through an orifice 61 on that axis with the upper end of a central bore 62 within the crankshaft 20. The lower end of the bore 62 connects with the top of the central bore 49. The bore 62 has a smaller diameter than that of the bore 49. The resistance to flow through the bore 62, the orifice 61, and the bore 60 is substantially greater than that through the bores 49 and 50.

The radial bore 60, the orifice 61, and the axial bore 62 form a centrifugal gas pump, drawing gas from the inlet of the oil pump bore 49, and discharging the gas into the compressor interior above the oil sump and above the plate 57. The constriction provided by the orifice 61, and centrifugal force, greatly restrain the flow of the heavier oil through the gas pump. Increased centrifugal force and therefore a larger pumping head is provided by the relatively long radial gas pump bore 60.

The previously mentioned Ayling-Thayer US. Pat. No. 3,388,855 discloses an orifice between the inlet of an oil pump and the inlet of a gas vent passage but that orifice is not on the axis of the crankshaft, the gas vent bore is relatively short, and the latter discharges gas into an oil sump below the level of the oil therein. The U. S. Pats. Nos. 3,182,901 of B. E. Solomon, and 3,279,683 of E. W Kleinlein disclose radial gas pumping passages connected through axial passages to the inlets of oil pumps, but their gas pumping passages are not constricted, do not contain orifices, and do not extend through counterweights. The advantages of the orifice on the axis of the crankshaft are that the constriction not only greatly opposes oil flow, but the orifice vents at the center of rotation where the gas exists.

' The advantage of extending the radial gas pump bore through both the'crankshaft and the counterweight rather than just through a crankshaft, is that the gas pump bore is much longer, providing a much larger centrifugal head. This head is needed to prevent backflow from a pressurized crankcase when the compressor is operating, and it aids in priming the oil pump at start-up, especially when there is a very low oil level within the oil sump. The orifice also aids in priming the of the motor compartment 11 at the top of the crankshaft 20. Centrifugal force opposes the flow of the heavier oil through the transverse bore 71.

My previously mentioned US. Pat. No. 3,259,307 discloses a transverse gas pump bore connecting the top of an off-center bore to a central bore which extends to the top of a crankshaft. The present invention has the advantage that the transverse bore is longer,

oil pump by backing up the oil drawn into the axial bores by the rotation of the gas pump bore.

The. present invention also adds for venting accumulated gas fromthe off-center bore 51 at the upper bearings 42 and 43, a central gas passage 70 within the key 18, the top of which connects with the upper portion of the motor compartment 11 at the top of the crankshaft 20, and the bottom of which connects with the keyway 19 below the key 18, and adds a transverse bore 71 within the crankshaft 20 which connects with and crosses the top of the off-center bore 51. One end of the transverse bore 71 connects with the upper bearing 43, and its other end connects with the keyway 19 below the hollow key 18. The transverse bore slopes upwardly from where it connects with the bearing 43, and crosses the axis of the crankshaft 20. A ball 72 actproviding a greater pumping head, and the cost of deep drilling a center bore is avoided by using an existing keyway and a hollow key within the latter.

The U. S. Pats. Nos. 3,098,604 of C. A. Dubberley, and 3,162,360 of G. T. Privon et al disclose transverse gas pump bores connected to the tops of off-center bores, and connected through downwardly extending counter-bores within the rotors of electric motors with motor compartments below the rotors. The present invention has the advantage over those of the Dubberley and Privon et al. patents in that through discharging the vented gas into the top of a motor compartment instead of into the bottom of the latter, the effect of suction gas pressure drop across the motor which might draw oil through the gas vent passages, is avoided.

I claim:

1. In a refrigerant compressor having a shell with an oil sump in its bottom, having a crankshaft extending upwardly above said sump with its bottom within said sump, said crankshaft having a central bore in its lower portion connecting with said sump, having a longitudinal off-center bore, having a radial bore extending from said off-center bore to said central bore, and having a second radial bore above said first mentioned radial bore with its outer end connecting with the interior of said shell above said sump and with its inner end adjacent to the axis of said crankshaft, the improvement comprising:

the provision of passage means including constriction means providing substantially more resistance to flow therethrough than through said central and said first mentioned radial bores connecting said inner end of said second radial bore to the top of said central bore.

2. The invention claimed in claim 1 in which:

said constriction means comprises an orifice on the axis of said crankshaft below said inner end of said second radial bore.

3. The invention claimed in claim 2 in which said crankshaft has a counterweight thereon, and in which:

said second radial bore extends through said counterweight.

4. The invention claimed in claim 1 in which said crankshaft has a counterweight thereon, and in which:

said second radial bore extends through said counterweight.

5. The invention claimed in claim 4 in which: there is provided a transverse bore extending through said crankshaft, connected to the top of said off-center bore, and crossing said axis, and

there is provided a longitudinal passage at the surface of said crankshaft connected to said transverse bore, and having an open end at the top of said crankshaft.

6. The invention claimed in claim 3 in which:

there is provided a transverse bore extending through said crankshaft, connected to the top of said offcenter bore, and crossing said axis, and there is provided a longitudinal passage at the surface of said crankshaft connected to said trans-verse bore, and having an open end at the top of said crankshaft.

7. The invention claimed in claim 2 in which:

there is provided a transverse bore extending through said crankshaft, connected to the top of said offcenter bore, and crossing said axis, and

there is provided a longitudinal passage at the surface of said crankshaft connected to said transverse bore, and having an open end at the top of said crankshaft.

8. The invention claimed in claim 1 in which:

there is provided a transverse bore extending through said crankshaft, connected to the top of said offcenter bore, and crossing said axis, and

there is provided a longitudinal passage at the surface of said crankshaft connected to said transverse bore, and having an open end at the top of said crankshaft.

9. The invention claimed in claim 8 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which:

there is provided a keyway in said crankshaft and said rotor opposite said off-center bore,

there is provided a hollow key in said keyway, and in which:

said longitudinal passage comprises a portion of said keyway below said key and the opening within said key.

10. The invention claimed in claim 7 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which:

there is provided a keyway in said crankshaft and said rotor opposite said off-center bore,

there is provided a hollow key in said keyway, and in which:

said longitudinal passage comprises a portion of said keyway below said key and the opening within said key.

11. The invention claimed in claim 6 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which:

there is provided a keyway in said crankshaft and said rotor opposite said off-center bore,

there is provided a hollow key in said keyway, and in which:

said longitudinal passage comprises a portion of said keyway below said key and the opening within said key.

12. The invention claimed in claim 5 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which:

there is provided a keyway in said crankshaft and said rotor opposite said off-center bore,

there is provided a hollow key in said keyway, and in which:

said longitudinal passage comprises a portion of said keyway below said key, and the opening within said key.

13. in a refrigerant compressor having a shell with an oil sump in its bottom, having a crankshaft extending upwardly above said sump with its bottom within said sump, having an off-center bore, and having oil pumping means connected to said sump and to said bore, the improvement comprising:

the provision of a transverse bore within said crankshaft connected to the top of said bore and crossing the axis of said crankshaft, and

the provision of means forming a longitudinal passage at the surface of said crankshaft opposite said off-center bore, connected to said transverse bore, and having an open end at the top of said crankshaft.

14. The invention claimed in claim 13 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which:

said longitudinal passage comprises a keyway in said crankshaft and said rotor, and a hollow key within said keyway. 

1. In a refrigerant compressor having a shell with an oil sump in its bottom, having a crankshaft extending upwardly above said sump with its bottom within said sump, said crankshaft having a central bore in its lower portion connecting with said sump, having a longitudinal off-center bore, having a radial bore extending from said off-center bore to said central bore, and having a second radial bore above said first mentioned radial bore with its outer end connecting with the interior of said shell above said sump and with its inner end adjacent to the axis of said crankshaft, the improvement comprising: the provision of passage means including constriction means providing substantially more resistance to flow therethrough than through said central and said first mentioned radial bores connecting said inner end of said second radial bore to the top of said central bore.
 2. The invention claimed in claim 1 in which: said constriction means comprises an orifice on the axis of said crankshaft below said inner end of said second radial bore.
 3. The invention claimed in claim 2 in which said crankshaft has a counterweight thereon, and in which: said second radial bore extends through said counterweight.
 4. The invention claimed in claim 1 in which said crankshaft has a counterweight thereon, and in which: said second radial bore extends through said counterweight.
 5. The invention claimed in claim 4 in which: there is provided a transverse bore extending through said crankshaft, connected to the top of said off-center bore, and crossing said axis, and there is provided a longitudinal passage at the surface of said crankshaft connected to said transverse bore, and having an open end at the top of said crankshaft.
 6. The invention claimed in claim 3 in which: there is provided a transverse bore extending through said crankshaft, connected to the top of said off-center bore, and crossing said axis, and there is provided a longitudinal passage at the surface of said crankshaft connected to said transverse bore, and having an open end at the top of said crankshaft.
 7. The invention claimed in claim 2 in which: there is provided a transverse bore extending through said crankshaft, connected to the top of said off-center bore, and crossing said axis, and there is provided a longitudinal passage at the surface of said crankshaft connected to said transverse bore, and having an open end at the top of said crankshaft.
 8. The invention claimed in claim 1 in which: there is provided a transverse bore extending through said crankshaft, connected to the top of said off-center bore, and crossing said axis, and there iS provided a longitudinal passage at the surface of said crankshaft connected to said transverse bore, and having an open end at the top of said crankshaft.
 9. The invention claimed in claim 8 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which: there is provided a keyway in said crankshaft and said rotor opposite said off-center bore, there is provided a hollow key in said keyway, and in which: said longitudinal passage comprises a portion of said keyway below said key and the opening within said key.
 10. The invention claimed in claim 7 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which: there is provided a keyway in said crankshaft and said rotor opposite said off-center bore, there is provided a hollow key in said keyway, and in which: said longitudinal passage comprises a portion of said keyway below said key and the opening within said key.
 11. The invention claimed in claim 6 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which: there is provided a keyway in said crankshaft and said rotor opposite said off-center bore, there is provided a hollow key in said keyway, and in which: said longitudinal passage comprises a portion of said keyway below said key and the opening within said key.
 12. The invention claimed in claim 5 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which: there is provided a keyway in said crankshaft and said rotor opposite said off-center bore, there is provided a hollow key in said keyway, and in which: said longitudinal passage comprises a portion of said keyway below said key, and the opening within said key.
 13. In a refrigerant compressor having a shell with an oil sump in its bottom, having a crankshaft extending upwardly above said sump with its bottom within said sump, having an off-center bore, and having oil pumping means connected to said sump and to said bore, the improvement comprising: the provision of a transverse bore within said crankshaft connected to the top of said bore and crossing the axis of said crankshaft, and the provision of means forming a longitudinal passage at the surface of said crankshaft opposite said off-center bore, connected to said transverse bore, and having an open end at the top of said crankshaft.
 14. The invention claimed in claim 13 in which said compressor has the rotor of an electric motor on the upper portion of said crankshaft, and in which: said longitudinal passage comprises a keyway in said crankshaft and said rotor, and a hollow key within said keyway. 